Cook the chicken gently: Place the whole chicken breast in a pot of cold water, bring to a gentle simmer, then keep on low heat for 8–10 minutes. Turn off the heat, cover the pot, and let it rest for 5 more minutes. This slow, gentle cooking method keeps the meat juicy and prevents the dry, rubbery texture that ruins most diet chicken dishes. Transfer to ice water to cool completely before handling
Prep the vegetables: Cut cucumber into thin, even strips. If you prefer cooked bell pepper over raw, blanch the pepper strips in boiling water for 30 seconds, then shock in cold water to lock in crisp-tender texture. Mince garlic, chop green onion and cilantro, and set all aside
Shred by hand for best texture: Tear the cooled chicken breast into thin, uniform strips following its natural muscle grain. Hand-shredding creates more surface area for the dressing to cling to, so every bite picks up more flavor than sliced chicken
Toss and finish: Combine chicken shreds, cucumber strips and bell pepper strips in a large bowl. Add oyster sauce, light soy sauce, salt, thirteen-spice powder, ginger powder, minced garlic and green onion. Toss thoroughly until all ingredients are evenly coated. Top with cilantro and a light drizzle of chili oil if desired. For the most refreshing taste, chill in the refrigerator for 10 minutes before serving